In order to make customers choose the constant temperature and humidity chamber reasonably and correctly, today we will share how to choose the Size and Control Method of it.
Part Ⅰ: How to choose the Size of the constant temperature and humidity chamber?
When the tested product (components or complete machine) is put into the constant temperature and humidity chamber for testing, in order to ensure that the surrounding atmosphere of the tested product can meet the environmental test conditions specified in the test specification, the working size of the chamber should be adapt to the tested product.The following rules should be followed between the outer dimensions:
A) The volume of the tested product (W×D×H) shall not exceed (20～35%) of the effective working space of the test chamber (20% is recommended). It is recommended to select no more than 10% for products that generate heat during the test.
B) The ratio of the windward section area of the tested product to the total area of the test chamber working room on the section is not more than (35-50)% (35% is recommended).
C) Keep the distance between the outer surface of the tested product and the test chamber wall at least 100～120mm (120mm is recommended).
Part Ⅱ: How to choose the Control Method of the constant temperature and humidity chamber?
The control methods of the temperature and humidity test chamber include Fixed value test(FIX Method) and Program test(PROG Method).
Set a target temperature SP/SV. If it is a high temperature test, the meter will compare the SV with the actual measured value PV of the sensor. If the PV is lower than the SV , the meter OUT will output a 3~12V DC voltage to drive the SSR solid state The relay controls the heating of the heater to realize automatic control of the equipment. When the temperature is low, it is generally necessary to manually turn on the cooling button first, and the working room is cooled down until the actual negotiated temperature PV is close to the target value SV. The meter OUT outputs and starts to control the heating To balance the temperature and complete the control, the control action is a reverse action.
This control method is similar to the FIX Method, except that its set value (whether it is temperature or humidity) will change according to a preset program. The program test can be achieved by setting different switch signals at different stages to achieve compressor performance. Node control capabilities such as opening and closing, solenoid valve opening or closing. It has the ability to automatically keep constant temperature to the target temperature and humidity point and set the rate of raising and lowering temperature and humidity.
Post time: Feb-25-2021
